1. Field of the Invention
The present invention relates to a camera for determining exposure conditions and performing electronic flash control on the basis of fuzzy rules defined by a fuzzy theory using information such as a brightness distribution state of an object to be photographed, an object distance, and a focal length of a lens used.
2. Description of the Related Art
Various conventional cameras using a formula for evaluating photometric results have been proposed wherein a brightness distribution state of an object to be photographed is measured by a plurality of photometric elements to determine an exposure value, as disclosed in Published Examined Japanese Utility Model Application No. 60-11475, Published Examined Japanese Patent Application Nos. 63-7331 and 62-39366, and Published Unexamined Japanese Patent Application Nos. 63-38119, 63-134922, and 63-134924.
In these conventional techniques, a determination value is used as a threshold value to perform classification and sorting with a formula so as to determine a back light state from a brightness distribution state of the object or an average or spot light measurement from the overall brightness. This threshold value and the classification are expressed in the form of values and formulas derived from actual experiences and knowledge. It is, however, very difficult to express the actual experiences and knowledge as digital values (crisp values).
When classification is performed based on many conditions such as the brightness distribution state of the object, the object distance, and the focal length of the lens, mathematical expressions are very complicated, and the number of classification items becomes large.
In addition, since a crisp value is used as a threshold value, a small increase from the crisp value causes a large increase in exposure value, thus resulting in an unnatural effect in practical photography. For this reason, in order to gradually change the exposure value, an interpolation operation is additionally performed, and the complicated operation is required.